Niemann-Pick disease can affect several parts of the body presenting a range of symptoms. There are three types of Neimann-Pick disease; type A, type B and type C which is based on the genetic cause and the symptoms evident. Neiman-Pick disease type C (NPC) develops when the body is not able to metabolize cholesterol and lipids within the cell. As the result, cholesterol can accumulate within the liver and the spleen causing its associated symptoms. The type C usually becomes evident in childhood although the symptoms may begin at any time. This disease is always fatal with death occurring in most of the cases before they reach the age 20. The later onset of the symptoms can result in longer lifespan although it is extremely rare for these individuals to reach age 40. There are only around 500 cases diagnosed globally.
Causes
The genetic mutation either in the NPC1 or NPC2 gene can cause this disease. The proteins that are produced by these genes are necessary for the movement of lipids within the cells. The genetic mutation results in the shortage of the functional protein which affects the normal movement of cholesterol and other lipids within the cells. Hence it can accumulate in the cells causing the dysfunction of cells leading to their death and resulting in the problems of various tissues and organ damage. This disease is inherited in an autosomal recessive pattern meaning both the copies of the gene in each cell are defective.
Symptoms
There is a considerable variation in the occurrence and the progression of the disease. It can develop prenatally, infantile, juvenile or as the adult onset. As every case appears to be unique and not all affected individuals present all of the symptoms of this disease. Some of the children can develop life-threatening complications early in life and others present mild form of the disease that may not be detected until adulthood. The accumulation of fluid in the fetal abdomen can be detected presenting severe interruption or suppression of the bile flowing from the liver. This can present jaundice, failure to thrive, enlarged liver and growth deficiency. When the lipid-containing cells accumulate in the lungs, it can cause life-threatening complications. Additional symptoms can include lack of muscle tone (hypotonia), delayed psychomotor development, seizures, hearing loss and the inability to move their eyes up and down. In the case of the neurological abnormalities, the symptoms can include lack of muscle coordination, presenting difficulties with balance, walking and speech. The psychiatric problems include progressive loss of memory and dementia. They can also have problems with swallowing eventually requiring a feeding tube.
Diagnosis
The diagnosis is based on the identification of characteristic features which will be confirmed with various diagnostic tests. The clinical testing includes staining the affected skin cells to determine the level of cholesterol accumulation. The genetic testing can also help identify the mutation responsible for the development of the disease.
Treatment
There is no cure for the disease and the treatment is based on the specific symptoms evident in each case. Swallowing difficulty needs to be monitored for aspiration and a speech therapist can help with the swallowing function. Additional treatment options include medications for anti-seizure, antidepressants and the central nervous system stimulants. Antipsychotic medications can treat psychosis.
References
https://rarediseases.org/rare-diseases/niemann-pick-disease-type-c/
https://ghr.nlm.nih.gov/condition/niemann-pick-disease#inheritance
https://medlineplus.gov/ency/article/001207.htm